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Abstract:

According to an aspect of the present invention, there is provided a
communication device including: an audio signal input member configured
to receive a first audio signal; a high-frequency coupler configured to
receive a second audio signal, the second audio signal based on a
high-frequency signal transmitted from an external high-frequency coupler
by communicating with the external high-frequency coupler through
electric field coupling; an output unit configured to output one of the
first audio signal and the second audio signal; and a switch configured
to switch an output of the output unit between the first audio signal and
the second audio signal based on a status of communication between the
high-frequency coupler and the external high-frequency coupler.

Claims:

1. A communication device comprising:an audio signal input member
configured to receive a first audio signal;a high-frequency coupler
configured to receive a second audio signal, the second audio signal
based on a high-frequency signal transmitted from an external
high-frequency coupler by communicating with the external high-frequency
coupler through electric field coupling;an output unit configured to
output one of the first audio signal and the second audio signal; anda
switch configured to switch an output of the output unit between the
first audio signal and the second audio signal based on a status of
communication between the high-frequency coupler and the external
high-frequency coupler.

2. The communication device of claim 1, wherein the switch is configured
to switch the output to the second audio signal when the high-frequency
coupler and the external high-frequency coupler communicates with each
other, and wherein the switch is configured to switch the output to the
first audio signal when the high-frequency coupler and the external
high-frequency coupler do not communicate with each other.

3. A communication device comprising:a microphone configured to receive a
third audio signal;a speaker configured to output a fourth audio signal;a
high-frequency coupler configured to communicate with an external
high-frequency coupler through electric field coupling by converting a
fifth audio signal into a high-frequency signal and transmitting the
high-frequency signal;an audio signal processor configured to transmit
the third audio signal to outside the communication device, the audio
signal processor configured to reproduce an incoming signal to output one
of the fourth audio signal and the fifth audio signal; anda switch
configured to switch an output of the audio signal processor between the
fourth audio signal and the fifth audio signal based on a status of
communication between the high-frequency coupler and the external
high-frequency coupler.

4. The communication device of claim 3, wherein:the high-frequency coupler
is configured to receive a sixth audio signal, the sixth audio signal
based on a high-frequency signal transmitted from the external
high-frequency coupler;the audio signal processor is configured to
transmit one of the third audio signal and the sixth audio signal to the
outside; andthe switch is configured to switch an input to the audio
signal processor between the third audio signal and the sixth audio
signal based on the status of communication between the high-frequency
coupler and the external high-frequency coupler.

5. A communication device comprising:an audio signal processor configured
to generate a seventh audio signal by reproducing audio information;a
high-frequency coupler configured to communicate with an external
high-frequency coupler through electric field coupling by receiving an
eighth audio signal, the eighth audio signal based on a high-frequency
signal transmitted from the external high-frequency coupler;an audio
signal output section configured to output one of the seventh audio
signal and the eighth audio signal; anda switch configured to switch an
output of the audio signal output section between the seventh audio
signal and the eighth audio signal based on a status of communication
between the high-frequency coupler and the external high-frequency
coupler.

6. The communication device of claim 1, wherein the high-frequency coupler
is configured to start to communicate with the external high-frequency
coupler without authentication processing.

7. The communication device of claim 3, wherein the high-frequency coupler
is configured to start to communicate with the external high-frequency
coupler without authentication processing.

8. The communication device of claim 5, wherein the high-frequency coupler
is configured to start to communicate with the external high-frequency
coupler without authentication processing.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001]This application is based upon and claims the benefit of priority
from Japanese Patent Application No. 2008-212450, filed on Aug. 21, 2008,
the entire contents of which are incorporated herein by reference.

BACKGROUND

[0002]1. Field

[0003]An aspect of the present invention relates to communication device.

[0004]2. Description of the Related Art

[0005]Communication devices are known which receive an audio signal from a
mobile phone that is equipped with an induction coil (see
JP-A-2007-325042, for instance).

[0006]A communication device of this kind is equipped with a telephone
coil for receiving an audio signal from a mobile phone, an amplifier for
amplifying the signal received by the telephone coil, and a speaker for
converting the signal amplified by the amplifier into a voice and
outputting it. When a mobile phone having an induction coil is brought
into close proximity to the communication device, the telephone coil is
magnetically coupled with the induction coil, whereby an audio signal of
the mobile phone can be output from the speaker of the communication
device. If this type of communication device is applied to, for example,
a hearing aid, a user can make a call while wearing the hearing aid.

[0007]However, when a communication device of the above kind is applied to
a hearing aid, a signal input from a functional unit of the hearing aid
and a signal input from the telephone coil are superimposed and amplified
in the amplifier, and then converted by the speaker, as a result of which
an audio including two input superimposed each other is output from the
speaker. Therefore, it may be difficult for a user to distinguish two
original voices from each other.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0008]A general architecture that implements the various feature of the
present invention will now be described with reference to the drawings.
The drawings and the associated descriptions are provided to illustrate
embodiments of the present invention and not to limit the scope of the
present invention.

[0009]FIG. 1 is a schematic view showing an example configuration of a
communication system according to a first embodiment;

[0010]FIG. 2 is a sectional view showing an example configuration of a
first communication device according to the first embodiment;

[0011]FIG. 3 is a block diagram showing an example configuration of the
first communication device according to the first embodiment;

[0012]FIG. 4 is a block diagram showing an example configuration of a
second communication device according to the first embodiment;

[0013]FIG. 5 is a schematic view showing an example operation of the
communication devices according to the first embodiment;

[0014]FIG. 6A is an exemplary flowchart showing the operation of the first
communication device according to the first embodiment;

[0015]FIG. 6B is an exemplary flowchart showing the operation of the
second communication device according to the first embodiment;

[0016]FIG. 7 is a schematic view showing an example configuration of a
communication system according to a second embodiment;

[0017]FIG. 8 is a block diagram showing an example configuration of a
third communication device according to the second embodiment;

[0018]FIG. 9 is a block diagram showing an example configuration of a
fourth communication device according to the second embodiment;

[0019]FIG. 10 is a schematic view showing an example operation of the
communication devices according to the second embodiment;

[0020]FIG. 11A is an exemplary flowchart showing the operation of the
third communication device according to the second embodiment; and

[0021]FIG. 11B is an exemplary flowchart showing the operation of the
fourth communication device according to the second embodiment.

DETAILED DESCRIPTION

[0022]Various embodiments according to the present invention will be
described hereinafter with reference to the accompanying drawings. In
general, according to one embodiment of the present invention, there is
provided a communication device including: an audio signal input member
configured to receive a first audio signal; a high-frequency coupler
configured to receive a second audio signal, the second audio signal
based on a high-frequency signal transmitted from an external
high-frequency coupler by communicating with the external high-frequency
coupler through electric field coupling; an output unit configured to
output one of the first audio signal and the second audio signal; and a
switch configured to switch an output of the output unit between the
first audio signal and the second audio signal based on a status of
communication between the high-frequency coupler and the external
high-frequency coupler.

[0023]Communication devices according to embodiments of the present
invention will be hereinafter described in detail with reference to the
drawings.

First Embodiment

[0024](Configuration of Communication System)

[0025]FIG. 1 is a schematic view showing an example configuration of a
communication system according to a first embodiment.

[0026]A communication system 100A is configured of headphones 1A which
output a voice when connected to an audio reproducing device 3A and also
function as a communication device and a mobile phone 2A which functions
as not only a mobile phone but also a communication device.

[0027]The headphones 1A are equipped with a left-ear pad 1D to be attached
to the left ear of a user, a right-ear pad 1E to be attached to the right
ear of the user, and a head band 1C which connects the left-ear pad 1D
and the right-ear pad 1E mechanically and electrically. And the
headphones 1A are connected to the audio reproducing device 3A via an
audio/remote control signal line 12. The left-ear pad 1D is equipped with
a high-frequency coupler 10 for communicating with an external device
through electric field coupling by a high-frequency signal, a speaker
unit 11L as an output unit for outputting a sound or voice, and the
audio/remote control signal line 12 as an input member. The right-ear pad
1E is equipped with a speaker unit 11R as an output unit for outputting a
sound or voice.

[0028]The mobile phone 2A is equipped with a high-frequency coupler 20 for
communicating with the high-frequency coupler 10; an earpiece 21 which
incorporates a speaker and serves as an output unit for outputting a
voice of an intended party when the mobile phone 2A functions as a mobile
phone; a mouth piece which incorporates a microphone and serves as an
input unit for receiving a voice to be transmitted to the intended party
when the mobile phone 2A functions as a mobile phone; a display 23 for
displaying a text, an image, or the like; and a manipulation unit 24
including plural switches.

[0029]In the embodiment, it is assumed that the high-frequency coupler 10
of the headphones 1A and the high-frequency coupler 20 of the mobile
phone 2A can communicate with each other when they are as close to each
other as 3 cm or less, for example, and that authentication processing
such as pairing or coding of a communication signal is not performed at a
start of a communication.

[0030]The audio reproducing device 3A, which is, for example, an MPEG
audio layer-3 (MP3) player having a hard disk drive (HDD), a flash
memory, or the like, outputs an audio signal to the headphones 1A via the
audio/remote control signal line 12.

[0031](Configuration of Communication Devices)

[0032]FIG. 2 is a sectional view showing an example configuration of a
first communication device (headphones 1A) according to the first
embodiment.

[0033]The left-ear pad 1D of the headphones 1A is equipped with the
high-frequency coupler 10, the speaker unit 11L, the audio/remote control
signal line 12, and a main circuit board 13 which is mounted with
electronic components such as a memory and a central processing unit
(CPU) for controlling operation of the headphones 1A. The right-ear pad
1E is equipped with the speaker unit 11R, a power circuit board 14 for
controlling power supply of the headphones 1A, a rechargeable battery 15
such as a lithium-ion battery which is chargeable and dischargeable, and
a power connector 16 to which a power source adapter for supplying power
is connected in charging the rechargeable battery 15. The head band 1C is
equipped, inside itself, with an audio signal line 17 which electrically
connects the main circuit board 13 to the speaker unit 11R and transmits
an audio signal to the latter, and a power line 18 which electrically
connects the power circuit board 14 to the main circuit board 13 and
supplies power to the latter.

[0034]FIG. 3 is a block diagram showing the example configuration of the
first communication device according to the first embodiment.

[0035]The main circuit board 13 of the headphones 1A is equipped with a
high-frequency signal processor 13a which is connected to the
high-frequency coupler 10 and encodes and decodes a high-frequency
signal; a D/A converter 13b for converting a digital audio signal into an
analog audio signal; an audio path switch 13c for switching output
between an input signal A (first audio signal) from the audio/remote
control signal line 12 and an input signal B (second audio signal) from
the D/A converter 13b based on output from the high-frequency signal
processor 13a; an audio amplifier 13d as an audio signal processor for
amplifying an output audio signal of the audio path switch 13c and
outputs resulting signals to the speaker units 11L and 11R; and a remote
control signal generator 13e for generating a remote control signal under
the control of the high-frequency signal processor 13a and transmitting
it through the audio/remote control signal line 12.

[0036]FIG. 4 is a block diagram showing an example configuration of a
second communication device (mobile phone 2A) according to the first
embodiment.

[0037]The mobile phone 2A is configured of the high-frequency coupler 20;
a high-frequency signal processor 20a which is connected to the
high-frequency coupler 20 and encodes and decodes a high frequency
signal; an audio path switch 20b for switching the output between an
output signal C (fourth audio signal) to a D/A converter 21c and an
output signal D (fifth audio signal) to the high-frequency signal
processor 20a; a speaker 21a which is incorporated in the earpiece 21; an
audio amplifier 21b for amplifying an audio signal received from a D/A
converter 21c and outputs a resulting signal to the speaker 21a; the D/A
converter 21c for converting a digital audio signal received from the
audio path switch 20b into an analog signal; a microphone 22a which is
incorporated in the mouthpiece 22; an A/D converter 22b for converting an
analog audio signal (third audio signal) received from the microphone 22a
into a digital signal; a cellular antenna 25 for transmitting and
receiving mobile phone radio waves; a cellular signal processor 26 as a
mobile phone signal processor which functions to enable a communication
with a distant user by means of radio waves transmitted and received by
the cellular antenna 25; and a CPU 27 for controlling the individual
sections.

[0038](Operation)

[0039]The operation of the communication devices according to the first
embodiment will be described below with reference to the drawings.

[0040]In the state shown in FIG. 1, the audio reproducing device 3A
reproduces, for example, audio information that is stored in a storage
unit provided in the main body and outputs a resulting audio signal. The
headphones 1A receive the audio signal that is output from the audio
reproducing device 3A via the audio/remote control signal line 12,
processes it with the audio path switch 13c and the audio amplifier 13d
in this order, and outputs sounds through the speaker units 11L and 11R.

[0041]In this case, not detecting establishment of a communication with an
external device, the high-frequency signal processor 13a controls the
audio path switch 13c to set the input to the audio path switch 13c to an
input signal A from the audio/remote control signal line 12.

[0042]Where the mobile phone 2A is used independently, an audio signal
output from the cellular signal processor 26 is sequentially processed by
the audio path switch 20b, the D/A converter 21c, and the audio amplifier
21b, and then output from the speaker 21a.

[0043]An audio signal to be input to the cellular signal processor 26 of
the mobile phone 2A is processed by the microphone 22a and the A/D
converter 22b in this order.

[0044]FIG. 5 is a schematic view showing an example operation of the
communication devices according to the first embodiment.

[0045]When a call arrives at the mobile phone 2A or a call is initiated by
the mobile phone 2A in the state shown in FIG. 5, the user brings the
earpiece 21 of the mobile phone 2A close to the left-ear pad 1D of the
headphones 1A. Since the mobile phone 2A and the headphones 1A are close
to each other, the high-frequency couplers 10 and 20 come as close to
each other as 3 cm or less, for example, whereby a communication is
established and an audio signal is transmitted.

[0046]In this case, when detecting the establishment of a communication
between the high-frequency couplers 10 and 20, the high-frequency signal
processor 13a controls the audio path switch 13c to set the input to the
audio path switch 13c as an input signal B from the D/A converter 13b.
Furthermore, the high-frequency signal processor 13a controls the remote
signal generator 13e to send a signal for stopping the reproduction to
the audio reproducing device 3A.

[0047]At this time, when detecting the establishment of a communication
between the high-frequency couplers 10 and 20, the high-frequency signal
processor 20a controls the audio path switch 20b to set the output from
the audio path switch 20b to an output signal D to the high-frequency
signal processor 20a.

[0048]As a result, an audio signal that is output from the cellular signal
processor 26 of the mobile phone 2A is sequentially processed by the
audio path switch 20b, the high-frequency signal processor 20a, the
high-frequency coupler 20, the high-frequency coupler 10, the
high-frequency signal processor 13a, the D/A converter 13b, the audio
path switch 13c, and the audio amplifier 13d, and then output from the
speaker units 11L and 11R.

[0049]An audio signal to be input to the cellular signal processor 26 of
the mobile phone 2A is processed by the microphone 22a and the A/D
converter 22b in this order.

[0050]FIG. 6A is an exemplary flowchart showing the operation of the first
communication device according to the first embodiment.

[0051]First, during ordinary use, at step S10 the high-frequency signal
processor 13a controls the audio path switch 13c to set the input to the
audio path switch 13c to an input signal A, that is, an audio signal that
is input through the audio/remote control signal line 12.

[0052]Then, the high-frequency signal processor 13a monitors the status of
the high-frequency coupler 10. When detecting establishment of a
communication with the external high-frequency coupler 20 (S11: yes), at
step S12 the high-frequency signal processor 13a sets the input to the
audio path switch 13c to an input signal B, that is, an audio signal that
is input from the D/A converter 13b.

[0053]When establishment of a communication through the high-frequency
coupler 10 is not detected (S11: no), the process returns to step S10,
where the input to the audio path switch 13c is set to an input signal A.

[0054]FIG. 6B is an exemplary flowchart showing the operation of the
second communication device according to the first embodiment.

[0055]First, during ordinary use, at step S15 the high-frequency signal
processor 20a sets the output of the audio path switch 20b to an output
signal C, that is, an audio signal to be output to the D/A converter 21c.

[0056]Then, the high-frequency signal processor 20a monitors the status of
the high-frequency coupler 20. When detecting establishment of a
communication with the external high-frequency coupler 10 (S16: yes), at
step S17 the high-frequency signal processor 20a sets the output of the
audio path switch 20b to an output signal D, that is, an audio signal to
be output to the high-frequency signal processor 20a.

[0057]When establishment of a communication through the high-frequency
coupler 20 is not detected (S16: no), the process returns to step S15,
where the output of the audio path switch 20b is set to an output signal
C.

[0058](Advantages of First Embodiment)

[0059]In the above-described embodiment, when the mobile phone 1A is held
close to the left-ear pad 1D of the headphones 1A, that is, when the
high-frequency coupler 10 of the headphones 1A and the high-frequency
coupler 20 of the mobile phone 2A have established a communication, the
audio path switches 13c and 20b switch the audio signal input and output,
respectively. This allows a user to easily distinguish between a voice
from the mobile phone 2A and a sound from the audio reproducing device 3A
through the headphones 1A. That is, the user can use the mobile phone 2A
and the audio reproducing device 3A while wearing the headphones 1A.

[0060]Since the high-frequency couplers 10 and 20 do not perform
authentication processing such as pairing or coding, no operation for
establishment of a connection needs to be performed in switching between
the mobile phone 2A and the audio reproducing device 3A, accordingly,
time required for the switching can be shortened. Since a communication
can be made without registration between devices, the operation according
to the embodiment can be performed between arbitrary devices.

[0061]Since the high-frequency couplers 10 and 20 start a communication
when they are brought close to one ear of a user, the sense of
manipulation of the mobile phone 2A is not impaired.

[0062]When a communication through the high-frequency coupler 10 finishes,
the high-frequency signal processor 13a may control the remote control
signal generator 13e to send a signal for restarting reproduction of
audio information to the audio-reproducing device 3A.

[0063]A communication between the headphones 1A and the audio reproducing
device 3A may be a radio communication using Bluetooth (registered
trademark), a wireless LAN, or the like rather than a wired communication
using the audio/remote control signal line 12.

Second Embodiment

[0064]FIG. 7 is a schematic view showing an example configuration of a
communication system according to a second embodiment. A component having
the same structure or function as a corresponding component in the first
embodiment will be given the same reference symbol as the latter.

[0065]The audio/remote control signal line 12 of headphones 1B has a
microphone 19 for collecting a voice of a user of the headphones 1B and
outputs a resulting audio signal. The headphones 1B are different from
the headphones 1A in not having the high-frequency coupler 10.

[0066]An audio reproducing device 3B as a communication device is equipped
with a high-frequency coupler 30 for communicating with the
high-frequency coupler 20.

[0067]FIG. 8 is a block diagram showing an example configuration of a
third communication device (audio reproducing device 3B) according to the
second embodiment.

[0068]The audio reproducing device 3B is equipped with the high-frequency
coupler 30; a high-frequency signal processor 30a which is connected to
the high-frequency coupler 30 and encodes and decodes a high-frequency
signal; a headphone jack 31a as an output terminal which is connected to
the headphones 1B; a headphone amplifier 31b for amplifying an audio
signal to be output according to the characteristics of the headphones
1B; a D/A converter 31c for converting a digital audio signal that is
input from an audio path switch 36 into an analog audio signal; a
microphone jack 32a as an input terminal which is connected to the
microphone 19 of the headphones 1B; a microphone amplifier 32b for
amplifying an audio signal that is input from the microphone 19; an A/D
converter 32c for converting an analog audio signal that is input from
the microphone amplifier 32b into a digital audio signal; a CPU 33 for
controlling the individual sections; an HDD 34 for storing audio
information; a digital signal processor (DSP) 35 for causing an MP3
decoder 35a to operate, the MP3 decoder 35a being an audio information
reproduction processor for decoding audio information stored in the HDD
34 and performing signal processing on a resulting signal; and the audio
path switch 36 for switching the input between an input signal E (seventh
audio signal) from the DSP 35 and an input signal F (eighth audio signal)
from the high-frequency signal processor 30a.

[0069]FIG. 9 is a block diagram showing an example configuration of a
fourth communication device (mobile phone 2B) according to the second
embodiment.

[0070]The mobile phone 2B is equipped with an audio path switch 20d for
switching the input between an input signal I (third audio signal) from
the A/D converter 22b and an input signal J (sixth audio signal) from the
high-frequency signal processor 20a and an audio path switch 20c for
switching the output between an output signal G (fourth audio signal) to
the D/A converter 21c and an output signal H (fifth audio signal) to the
high-frequency signal processor 20a.

[0071](Operation)

[0072]The operation of the communication devices according to the second
embodiment will be described below with reference to the drawings.

[0073]In the state shown in FIG. 7, the audio reproducing device 3B
reproduces audio information of the HDD 34 with the MP3 decoder 35a of
the DSP 35, processes a resulting audio signal with the audio path switch
36, the D/A converter 31c, and the headphone amplifier 31b in this order,
and outputs the thus-processed audio signal from the headphone jack 31a.
The headphones 1B receive, via the audio/remote control signal line 12,
the audio signal that is output from the headphone jack 31a of the audio
reproducing device 3B, process it with the audio path switch 13c and the
audio amplifier 13d in this order, and output sounds through the speaker
units 11L and 11R.

[0074]In this case, not detecting establishment of a communication with an
external device, the high-frequency signal processor 30a controls the
audio path switch 36 to set the input to the audio path switch 36 to an
input signal E from the DSP 35.

[0075]When the mobile phone 2B is used independently, an audio signal
output from the cellular signal processor 26 is sequentially processed by
the audio path switch 20c, the D/A converter 21c, and the audio amplifier
21b, and then output from the speaker 21a.

[0076]An audio signal to be input to the cellular signal processor 26 of
the mobile phone 2B is processed by the microphone 22a and the A/D
converter 22b in this order.

[0077]FIG. 10 is a schematic view showing an example operation of the
communication devices according to the second embodiment.

[0078]When a call arrives at the mobile phone 2B or a call is initiated by
the mobile phone 2B in the state shown in FIG. 7, the user brings the
mobile phone 2A close to the audio reproducing device 3B. A communication
is started when the high-frequency couplers 20 and 30 come as close to
each other as 3 cm or less.

[0079]In this case, when detecting the establishment of a communication,
the high-frequency signal processor 30a controls the audio path switch 36
to switch the input to the audio path switch 36 from an input signal E
from the DSP 35 to an input signal F from the high-frequency signal
processor 30a. Furthermore, the audio path switch 36 inputs an audio
signal that has been processed by the microphone jack 32a, the microphone
amplifier 32b, and the A/D converter 32c in this order to the
high-frequency signal processor 30a.

[0080]At this time, when detecting the establishment of a communication,
the high-frequency signal processor 20a controls the audio path switch
20c to set the output from the audio path switch 20c to an output signal
H to the high-frequency signal processor 20a. Furthermore, the
high-frequency signal processor 20a controls the audio path switch 20d to
set the input to the audio path switch 20d to an input signal J from the
high-frequency signal processor 20a. The cellular signal processor 26 may
receive a speech signal of the call at the time of the switching of the
audio path switch 20d.

[0081]As a result of the above operation, an audio signal that is output
from the cellular signal processor 26 of the mobile phone 2B is processed
by the audio path switch 20c, the high-frequency signal processor 20a,
the high-frequency coupler 20, the high-frequency coupler 30, the
high-frequency signal processor 30a, the audio path switch 36, the D/A
converter 31c, and the headphone amplifier 31b in this order, and a
resulting audio signal is output from the headphone jack 31a. The audio
signal that is output from the headphone jack 31a is output as a voice
through the speaker units 11L and 11R of the headphones 1B.

[0082]An audio signal to be input to the cellular signal processor 26 of
the mobile phone 2B is processed by the microphone 19 of the headphones
1B, the audio/remote control signal line 12, the microphone jack 32a, the
microphone amplifier 32b, the A/D converter 32c, audio path switch 36,
the high-frequency signal processor 30a, the high-frequency coupler 30,
the high-frequency coupler 20, the high-frequency signal processor 20a,
and the audio path switch 20d in this order.

[0083]FIG. 11A is an exemplary flowchart showing the operation of the
third communication device according to the second embodiment.

[0084]First, during ordinary use, at step S20 the high-frequency signal
processor 30a controls the audio path switch 36 to set the input to the
audio path switch 36 to an input signal E, that is, an audio signal that
is input from the DSP 35.

[0085]Then, the high-frequency signal processor 30a monitors the status of
the high-frequency coupler 30. When detecting establishment of a
communication with the external high-frequency coupler 20 (S21: yes), at
step S22 the high-frequency signal processor 30a sets the input to the
audio path switch 36 to an input signal F, that is, an audio signal that
is input from the high-frequency signal processor 30a.

[0086]When establishment of a communication through the high-frequency
coupler 30 is not detected (S21: no), the process returns to step S20,
where the input to the audio path switch 36 is set to an input signal E.

[0087]FIG. 11B is an exemplary flowchart showing the operation of the
fourth communication device according to the second embodiment.

[0088]First, during ordinary use, at step S25 the high-frequency signal
processor 20a sets the input of the audio path switch 20d to an input
signal I, that is, an audio signal that is input from the A/D converter
22b, and sets the output of the audio path switch 20c to an output signal
G, that is, an audio signal to be output to the D/A converter 21c.

[0089]Then, the high-frequency signal processor 20a monitors the status of
the high-frequency coupler 20. When detecting establishment of a
communication with the external high-frequency coupler 10 (S26: yes), at
step S27 the high-frequency signal processor 20a sets the input to the
audio path switch 20d to an input signal J, that is, an audio signal that
is input from the high-frequency signal processor 20a, and sets the
output of the audio path switch 20c to an output signal H, that is, an
audio signal to be output to the high-frequency signal processor 20a.

[0090]When establishment of a communication through the high-frequency
coupler 20 is not detected (S26: no), the process returns to step S25,
where the input to the audio path switch 20d is set to an input signal I
and the output of the audio path switch 20c is set to an output signal G.

[0091](Advantages of Second Embodiment)

[0092]In the above-described embodiment, when the mobile phone 1B is held
close to the audio reproducing device 3B, that is, when the
high-frequency coupler 30 of the audio reproducing device 3B and the
high-frequency coupler 20 of the mobile phone 2B have established a
communication, the audio path switches 20c and 20d switch the audio
signal output and input, respectively, and the audio path switch 36
switches the audio signal input. This allows a user to easily distinguish
between voice from the mobile phone 2B and a sound from the audio
reproducing device 3B through the headphones 1B. That is, the user can
use the mobile phone 2B and the audio reproducing device 3B while wearing
the headphones 1B.

[0093]The headphones 1B may be arbitrary headphones as long as they are
equipped with speakers and a microphone. The pair of speakers and the
microphone may be connected as separate members.

[0094]A communication may be configured in such a manner that the
high-frequency coupler 30, the high-frequency signal processor 30a, and
the audio path switch 36 of the audio reproducing device 3B are made
independent of the remaining part and implemented as a separate dongle
that can be connected to the remaining part. This makes it possible to
give a general-purpose audio reproducing device a communication function
and an audio path switching function. The similar sections of the mobile
phone 2B may be made separately.

[0095](1) A first aspect of the invention provides a communication device
including: an audio signal input member configured to receive a first
audio signal; a high-frequency coupler configured to receive a second
audio signal, the second audio signal based on a high-frequency signal
transmitted from an external high-frequency coupler by communicating with
the external high-frequency coupler through electric field coupling; an
output unit configured to output the first audio signal or the second
audio signal; and a switch configured to switch the output of the output
unit between the first audio signal and the second audio signal based on
a status of communication between the high-frequency coupler and the
external high-frequency coupler.

[0096]With this configuration, when the high-frequency coupler has started
to communicate with an external device, the audio signal input source is
switched from the audio signal input member to the high-frequency
coupler. Therefore, the audio signal output from the output unit is not
audio signals that are superimposed each other. This allows a user to
recognize the output audio signal properly.

[0097](2) A second aspect of the invention provides a communication device
including a microphone configured to receive a third audio signal; a
speaker configured to output a fourth audio signal; a high-frequency
coupler configured to convert a fifth audio signal into a high-frequency
signal and to transmit the high-frequency signal by communicating with an
external high-frequency coupler through electric field coupling; an audio
signal processor configured to transmit the third audio signal as a
speech signal to outside the communication device, the audio signal
processor configured to reproduce an incoming speech signal received
externally and output the reproduced speech signal as the fourth audio
signal or the fifth audio signal; and a switch configured to switch the
output of the audio signal processor between the fourth audio signal and
the fifth audio signal based on a status of communication between the
high-frequency coupler and the external high-frequency coupler.

[0098]With this configuration, when the high-frequency coupler has started
to communicate with an external device, the output destination of an
audio signal produced by reproducing a speech signal by the audio signal
processor is switched from the speaker to the high-frequency coupler.
This allows the external device having a high-frequency coupler to output
an audio signal based on the speech signal.

[0099](3) A third aspect of the invention provides a communication device
including: an audio signal processor configured to generate a seventh
audio signal by reproducing audio information; a high-frequency coupler
configured to receive an eighth audio signal, the eighth audio signal
based on a high-frequency signal transmitted from an external
high-frequency coupler by communicating with the external high-frequency
coupler through electric field coupling; an audio signal output section
configured to output the seventh audio signal or the eighth audio signal;
and a switch configured to switch the output of the audio signal output
section between the seventh audio signal and the eighth audio signal
based on a status of communication between the high-frequency coupler and
the external high-frequency coupler.

[0100]With this configuration, when the high-frequency coupler has started
to communicate with an external device, the audio signal output of the
audio signal output section is switched from an audio signal reproduced
by and output from the audio signal processor to an audio signal received
by the high-frequency coupler. This allows the audio signal output
section to output an audio signal to be reproduced by the external device
having a high-frequency coupler.

[0101]One aspect of the invention makes it possible to input or output
plural kinds of audio signals selectively according to a use situation of
the communication device.